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Date: Tue, 4 Jun 2013 12:09:29 -0400 From: Theodore Ts'o <tytso@....edu> To: Jan Kara <jack@...e.cz> Cc: linux-ext4@...r.kernel.org Subject: Re: [PATCH 04/26] jbd2: Refine waiting for shadow buffers On Fri, May 31, 2013 at 11:42:37AM +0200, Jan Kara wrote: > Currently when we add a buffer to a transaction, we wait until the > buffer is removed from BJ_Shadow list (so that we prevent any changes to > the buffer that is just written to the journal). This can take > unnecessarily long as a lot happens between the time the buffer is > submitted to the journal and the time when we remove the buffer from > BJ_Shadow list (e.g. we wait for all data buffers in the transaction, > we issue a cache flush etc.). Also this creates a dependency of > do_get_write_access() on transaction commit (namely waiting for data IO > to complete) which we want to avoid when implementing transaction > reservation. > > So we modify commit code to set new BH_Shadow flag when temporary > shadowing buffer is created and we clear that flag once IO on that > buffer is complete. This allows do_get_write_access() to wait only for > BH_Shadow bit and thus removes the dependency on data IO completion. > > Reviewed-by: Zheng Liu <wenqing.lz@...bao.com> > Signed-off-by: Jan Kara <jack@...e.cz> Applied, thanks. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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